Von Miller will only be eligible to play 10 regular season games in 2013. Photo: Reuters

When news broke Monday that Denver Broncos linebacker Von Miller was facing a four-game suspension for “violating NFL policy,” it was initially unclear whether the All-Pro had violated the league’s statutes against performance-enhancing drugs or substance abuse. Hours later, it appears as though Miller may have violated both by testing positive for both amphetamines and marijuana.

On Monday afternoon, Denver Post reporter Mike Klis noted that Miller, 24, had tested positive for both amphetamines and marijuana in 2011. The report comes just hours after ESPN’s Adam Schefter and Ed Werder reported that Miller would face a four-game suspension for violating an undisclosed NFL policy.

Amphetamines are an active ingredient in Adderall, a focus-enhancing drug that has recently resulted in a rash of suspensions among NFL players. If Miller did indeed test positive for amphetamines related to Adderall use, he faces an automatic four-game suspension, Pro Football Talk notes.

The NFL’s policies on marijuana use are a bit more relaxed. A player must commit two separate marijuana-related violations before facing a suspension, Pro Football Talk reports.

Miller’s pending four-game suspension has already progressed to the appeals process, and the Broncos star plans to fight the charges, ESPN reports. The league has yet to set a date for Miller’s official appeal. However, if the appeal fails, Miller will be forced to serve an immediate four-game suspension.

The loss of Miller would deal a blow to a Broncos defense that is already without the services of departed pass rusher Elvis Dumervil, who signed with the Baltimore Ravens during the offseason. Since Miller entered the NFL in 2011, only three other players have managed to outpace his 30 sacks.